Combination heat exchange head and combustion chamber



Feb. 18, 1958 e. B. HERBSTER 2,823,658

COMBINATION HEAT EXCHANGE HEAD AND COMBUSTION CHAMBER 2 Sheets-Sheet 1Filed May 12, ,1954

INVENTOR. 6. W

F 18, 1958" G. B. HERBSTER I 2,823,

COMBINATION HEAT EXCHANGE HEAD AND COMBUSTION CHAMBER 2 Sheets-Sheet 2Filed May 12, 1954 r r u .1

IN V EN TOR.

nitcd George B. Herbster, Dallas, Tex., assignor to Herbster- Schmiler,lnc., Cleveland, Ohio,.a corporation of Ohio Application May 12, 1954,Serial No. 429,215 9 Claims. Cl. 126-91 This invention relates to'heating apparatus which is an improvement in the heating apparatusdisclosed in United States Letters Patent No. 23314825, issued tome onMarch-23,'1943.

The present'invention relatesparticularly to the com bination heatexchange head'and combustion chamber of the exchanger disclosed in theabove patent and toe means for recuperatingheat from products ofcombustion discharged from the head;

More specifically, the present inventionrelates to a heat exchangerhaving a generally'upright heat'exchange head which iscomposedof aplurality of groups of tubes for heating media and whichextend'about acommon hOI'ir zontal axis, one group clockwise and one groupcounterclockwise. The tubes of' each group are spaced apart from eachother to provide therebetween, arcuate air passages which extend fromfrontto rearofthe headand' af ford passages for air through the head inintimate heat exchange relation with the tubes. An integral hollowcombustion chamber-is disposed'directly beneath the tubes and is incommunication, at its upper end with the lower end of-the tubes. Meansare provided for discharging the residua of-the heating media from thetubes at their upper ends. The improvement over the structure disclosedin the above patentresides'in the following: p

Connectors are provided in' the passages betwee'nthe tubes and extendacross the passages so as to assure an etlicient how of metal duringcastingof the combined heat and combustion chamber and to eliminate,chilling and cold spots in the metal in the mold cavity, and therebymaking possible the casting of' the entire structure in one piece, andcorrespondingly to eliminate hot spots and relieve the internal stressesin the metal during the heating and cooling of the head in subsequentuse.

The invention is further characterized in that the ribs are arranged onthe combustion chamber and cooperate with the connectors for increasingthe eifi'ciency ofthe new of metal during casting and' so for equalizingthermal stresses in the structure when the same is in use.

The invention is further characterized in that the addition to the twogroups of tubes, a central through tube is provided and is incommunication at its lower end with the combustion chamber and at itsupper end'with the exhaust outlet of the head and extends verticallyacross the space between the innermost clockwise extending tube andinnermost counterclockwise extending tube.

Another feature of the invention resides in. a fiuebaihje in connectionwith the heat exchanger. 7

Various objects and advantages ofthe invention willbecome apparent fromthe following description, wherein reference is made to'the drawings,in-which:

Figures 1, 2 and 3 are a front end elevation, left end elevation, andtop plan view, respectively, of av heater embodying the principles ofthe present invention; and

Figures 4, 5 and 6 are. a ,frontelevation, left side elevation, andtopplan view, respectively,.of.the heatexchanger gt the heaterillustrated in Figures4 through 6.; parts; of

2 Figures 4 and 5* being shown'in' section for clearness inillustration.

Referring first to Figures 1 through 3, the invention is shown embodiedin a heater or furnace which includes an outer casing I having at itstop-an openingZfor the discharge of. heated air from the casing, Mountedwithin the casing' l is an upright heat exchanger indicated generally at3 including as its upper portion aheat'exchange head land as its lowerportion a combustion chamber 5.

The combustion chamberis open at the bottom and is adapted to receivecombustible gaseousmedia from the burner 6 and provide-for thecombustion thereof without impingement ofv the flame-onthe inner wallsof the cham her 5' or head 4. The'chamber 5 is-openat the top so as toadmit the heated products from thechamber 5 into the head 4' at the baseof the latter. Air'is circulated through the casing and caused to passin heat exchange relation ship to the entire exchanger 3'by means of amotor driven blowerT; A The head" 4lias at. its upper end an exhaustpassage which isconnectedto a suitable flue. 9 which, in turn, leads tothe usual stack, not shown. I Referring next to'Figures 4 through 6, thehead of the exchanger comprises a plurality of generally upright groupsof arcuate tubes, one group extending clockwise and the other group'counterclockwise about a common horizontal axis, the'tubes extendingclockwise being indicated' at 11, 12 and 13;,resp'ectively, and thoseextending counterclockwise. being indicated. at 1'4, 1'5 and 1'6,'re-'spectively; All of the tubes are connected at their lower ends to theupper end of the combustion chamber'S.

The overall horizontal cross section of the head' 4" is elongated in. adirection generally transversely of the axis about which the tubesextendandis relatively narrow in a direction parallel to the axis. Thesame is true of the overall horizontal cross section of thechamber 5'.

, The tubes of each group are spaced apart from each other radially ofthe axis to provide circumferentially extending elongated passages 17and 18 between the tubes of the'cloekwise group and, 19 and 2'0"betweenthe tubes or the counterclockwise grou p I The passages 18 through 20extend entirely through the head from front to rear and'provide the airpassages for air passing in heat exchange relation'between the tubes. 7

The head 4. has at the top an outlet 21 with which all of, the tubescommunicate and which leadslto the flue 9' heretofore described.

, The combined head 4 and combustion chamber 5 comprising the exchanger3 is a one piece m'etali casting. However, in forming it as a one piececasting, considerable difficulty has been encountered due to cold spotsappearing in the metal in the mold cavity during casting, particularlywhen the structureris made in a sand mold.

' In order to eliminate these cold spots and the unequal chilling ofthemetal and to obtain a better flow of metal into the cavity, connectors.22 are provided between ad.- jacent tubes and ribs 23 are provided onthe walls of the combustion chamber 5,.

As shown in the drawings, the ribs 22 preferably are of solid metal andextend across the passages. between adjacent tubes. They intersect thetube walls. at abrupt angles; The connectors are preferably relativelythinin a direction endwi'se of'the tubes or circumferentially of thehead. Forwardly and rearwardly of the medial plane of the head, theyextend the major portion. of the dimension, of the head, preferably fromthe rear face almost to the forward face. They are arranged so that theinner end of, each connector is disposed, endwise of the tubes, close tothe outer end of a connector in the: next inwardlyadjacent passage. Forinstance, referring to the two upper right hand: connectors-.22 inFigure 4, thg

inner end of the uppermost connector 22 in the space 20 is disposed, ina direction endwise of the tube 15, close to the outer end of the upperconnector 22 in the space 19. The lower-connectors in each instance aresimilarly arranged. Each of the connectors 22 is spaced materially fromthe upper and lower ends of its associated passage between the tubes.The connectors pref erably are fairly uniformlydistributedcircumferentially of the head.

It is to be noted that the connectors in the inner pas sages, such asthe passages 17 and 19, extend more nearly radially than those in theouter passages 18 and 20. The connectors 22 in the same outer passageare substantially coplanar.

In the form illustrated in Figure 4, the connector in the outerpassages, such as 18 and 20, extend at an angle of about 15 to thevertical, respectively. The upper connector in the inner passage 17extends at about 15 to the vertical in a direction opposite to the upperconnector in the outer space 18 and the upper connector in the passage19 extends at about 15 to the vertical in a direction opposite from theupper connector in the outer space 20. The lower connectors in thespaces 17 and 19 slope downwardly and outwardly from the center of thehead, each at an angle of about 40 to the horizontal.

The ribs 23 of the combustion chamber are preferably disposed inapproximate alignment vertically with the lower ends of the tubes,respectively, and extend from the bottom of the combustion chambersubstantially to the lower ends of the tubes. These ribs are relativelythick forwardly and rearwardly of the head relative to the thickness ofthe walls thereof. They provide for a ready flow of molten metal intothe cavity during casting of the head as a unitary structure.

As to both the connectors 22 and the ribs 23, the same structures appearto increase greatly the radiating surface and the heat exchange from thehead to the air passing through the passages while at the same time theyreinforce the casting against internal stresses and warpage occasionedby successive periods of heating and cooling during use. They appear toeliminate excessively hot spots created by the products from the burner6 and render the head temperature more nearly uniform.

In addition to these modifications, a central tube 24 has been provided,the central tube being open at its lower end for receiving products fromthe combustion chamber and being open at its upper end for communicationwith the outlet 21. The inlet of the tube 24 is preferably just abovethe upper level of the inlets of the tubes 11 and 14 and its outlet ispreferably just below or at the lower level of the outlets of the tubes11 and 14. The tube 11 is preferably disposed midway between the tubes11 and 14 and extends vertically. All of the tubes are relatively narrowin cross section transversely of the axis of the head and relativelylong in cross section forwardly and rearwardly of the head.

With the tubes arranged in the manner recited, shortcircuiting of anundue proportion of the products from the combustion chamber through oneor more of the tubes and particularly through the tube 24, at theexpense of the others, is substantially eliminated, all of the tubesbeing heated approximately uniformly. By providing the connectors 22,ribs 23 and central tube 24, a much greater B. t. u. output and theheating ofa greater volume of air can be obtained with the exchanger ofthe present invention relative to that disclosed in the above mentionedpatent even when the heads have the same external dimensions.

' Referring to Figure 4, a number of sprue holes are indicated in dottedlines at S. These are the usual sprues from which metal is gated intothe mold cavity. As noted, these sprues are arranged generally at thefour corners of the cavity which is to form the head with the connectors22 and ribs 23; An efiicient flow of metal to all parts of the moldcavity is obtained when the exchanger illustrated is cast by metal fedfrom the four corners concurrently.

In the structure herein described, there are some cases, especially whenthe head is being taxed to capacity, when an appreciable amount of heatcan be recuperated from the part of flue 9 which passes through thecasing. Due to the structural arrangement and the manner in which thefurnace is to be located in the basement, it usually happens that theflue must extend generally horizontally from the heat exchange head 4 tothe stack and that it have between its ends a very abrupt bend, usuallyIt was found that the flue of this nature tended to heat to aconsiderably higher temperature along the margin the outside of the bendthan along the margin at the inside of the bend.

It has been found that by providing a baffle 25 in the flue, the heatingeffects on the flue of products from the head can be more nearlyequalized. When used, the baflle is located so near the flue wall to theinside of the bend and preferably extends from the inlet in the fluecontinuously to the outlet so as to divide the passage of the flue intotwo side by side passages, the one to the inner side of the bend beingof smaller cross section than the one to the outside of the bend.

In the form shown, for example, the flue is of rectangular cross sectionand the baflie 25 is parallel to the side walls thereof and extends fromthe top to the bottom of the passage through the flue. This baflle isarranged about /3 of the width of the flue outwardly from the side wallat the inside of the bend. When so arranged, the heating of the flueapproximates much more closely a uniform temperature at all portionsacross the flue than was theretofore obtained and exceedingly hightemperature spots were eliminated.

The carbon dioxide readings taken in the flue indicate that the carbondioxide is about the same at all portions transversely of the flue whenthe baflie is utilized whereas it varies materially from one side to theother when the baffle is not used. For example, prior to theintroduction of the baflie, the carbon dioxide reading varied from 8 atthe wall to the inside of the bend to 10 at the wall to the outside ofthe bend, whereas with the baffle, an average carbon dioxide reading ofabout 8.5 is obtained at all points transversely of the flue.

By the combination of the connectors, ribs, central tube 24 and bafllein the flue, a very high degree of efliciency in the exchange of heatfrom the gaseous heating media to the air is effected, the temperatureof the heat exchanger and of the flue is rendered more uniform, thecombination head and combustion chamber does not become distorted underrepeated heating and cooling, the heat exchange efficiency is increased,and the flow of molten metal into a mold for the combined head andcombustion chamber is facilitated so that rejects due to imperfectionsin casting are reduced to a minimum.

Having thus described my invention, I claim:

1. A heat exchanger and combustion chamber combination comprising agenerally upright head having a plurality of groups of substantiallyarcuate tubes for gaseous heating media, which tubes are concentric to.a horizontal axis and are open at the bottom to receive the heatingmedia and at the top to discharge the heating media, and which extendgenerally about their common axis whereby the heating media pass throughone group clockwise from the bottom to the top of the tubes and throughone group counter-clockwise from the bottom to the top of the tubes, thetubes of each group being radially spaced apart from each other toprovide therebetween elongated substantially concentric air passagesthrough the head from the front to the rear of the head, said headhaving walls forming a hollow downwardly opening combustion chamberdirectly beneath the bottom of the tubes and openings at its upper endinto the bottoms of the tubes and adapted to receive at the lowerportion secondary air and combustible gaseous fuel from a asaaees thetubes, metal ribs integral with the tubes and positioned with theircross sections, taken in vertical planes extending forwardly andrearwardly of the head, horizontal and said ribs forming connectorsacross the air passages between adjacent tubes, said connectors beingarranged one pair in each arcuate passage of each group, each connectorbeing joined along its longitudinal side margins at an abrupt angle toits associated tubes, respectively, each connector being relativelynarrow in cross-section in a direction circumferentially of itsassociated air passage and spaced a material distance from thecircumferential extremities of its associated air passage and extendingforwardly and rearwardly through the head the major portion of theforward and rearward extent of its associated air passage, a throughtube extending upwardly between the two innermost tubes and arranged toreceive at its lower end products from said chamber and to discharge thesame at its upper end, said through tube terminating at its lower end atleast as high as the upper level of the inlets of the adjacent arcuatetubes and terminating at its upper end substantially at the lower levelof the outlets of said adjacent arcuate tubes, all of the aforesaidstructure being a onepiece iron casting, and each of said connectorsbeing solid iron.

2. A heating head according to claim 1 characterized in that eachconnector in each outer passage has its inner side margin disposed, in aposition circumferentially of the tubes, close to the outer side marginof a connector in the next inwardly adjacent passage.

3. A heating head according to claim 1 characterized in that thecombustion chamber forming walls comprise generally upright front andrear walls, and a plurality of relatively thick ribs are providedexteriorly on, and integral with, said front and rear walls and extendfrom the lower end of the combustion chamber upwardly near to the levelof the lower ends of the tubes.

4. A heating head according to claim 3 characterized in that the ribsare in approximate alignment vertically with the lower ends of theirassociated tubes, respectively.

5. A heating head according to claim 1 characterized in that a throughtube is provided and extends upwardly between the two innermost tubes,and said through tube is arranged to receive products of combustion atits lower end and to discharge the same at its upper end.

6. A heating head according to claim 5 characterized in that all of thetubes are of substantially the same cross section.

7. A heating head according to claim 5 characterized in that saidthrough tube terminates at its lower end at least as high as the upperlevel of the inlets of the adj-acent arcuate tubes and terminates at itsupper end substantially at the lower level of the outlets of saidarcuate tubes.

8. A heat exchanger and combustion chamber combination comprising agenerally upright head having a plurality of groups of substantiallyarcuate, tubes for gaseous heating media, which tubes are concentric toa horizontal axis and are open at the bottom to receive the heatingmedia and at the top to discharge the heating media, and which extendgenerally about their common axis whereby the heating media pass throughone group clockwise from the bottom to the top of the tubes and throughone group counterclockwise from the bottom to the top of the tubes, thetubes of each group being radially spaced apart from each other toprovide therebetween elongated substantially concentric air passagesthrough the head from the front to the rear of the head, said headhaving walls forming a hollow downwardly opening combustion chamberdirectly beneath the bottom of the tubes and opening at its upper endinto the bottoms of the tubes and adapted to receive at the lowerportion secondary air and combustible gaseous fuel from a burner, saidhead having walls forming an outlet at its upper portion and connectedwith the tops of the tubes for conducting residua of the gaseous heatingmedia from the tubes, and a through tube extending upwardly between thetwo innermost tubes and arranged to receive at its lower end productsfrom said chamber and to discharge the same at its upper end, saidthrough tube terminating at its lower end at least as high as the upperlevel of the inlets of the adjacent arcuate tubes and terminating at itsupper end substantially at the lower level of the outlets of saidadjacent arcuate tubes.

9. A heat exchanger and combustion chamber combination comprising agenerally upright head having a plurality of groups of substantiallyarcuate tubes for gaseous heating media, which tubes are concentric to ahorizontal axis and are open at the bottom to receive the heating mediaand at the top to discharge the heating media, and which extendgenerally about their common axis whereby the heating media pass throughone group clockwise from the bottom to the top of the tubes and throughone group counter-clockwise from the bottom to the top of the tubes, thetubes of each group being radially spaced apart from each other toprovide, therebetween elongated substantially concentric air passagesthrough the head from the front to the rear of the head, said headhaving walls forming a hollow downwardly opening combustion chamberdirectly beneath the bottom of the tubes and opening at its upper endinto the bottoms of the tubes and adapted to receive at the lowerportion secondary air and combustible gaseous fuel from a burner, saidhead having walls forming an outlet at its upper portion and connectedwith the tops of the tubes for conducting residua of the gaseous heatingmedia from the tubes, metal ribs integral with the tubes and positionedwith their cross sections, taken in vertical planes extending forwardlyand rearwardly of the head, horizontal and said ribs forming connectorsacross the air passages between adjacent tubes, each connector beingjoined along its longitudinal side margins at an abrupt angle to itsassociated tubes, respectively, each connector being relatively narrowin cross section in a direction circumferentially of its associated airpassage and spaced a material distance from the circumferentialextremities of its associated air passage and extending forwardly andrearwardly through the head the major portion of the forward andrearward extent of its associated air passage, a through tube extendingupwardly between the two innermost tubes and arranged to receive at itslower end products from said chamber and to discharge the same at itsupper end, said through tube terminating at its lower end at least ashigh as the upper level of the inlets of the adjacent arcuate tubes andterminating at its upper end substantially at the lower level of theoutlets of said adjacent arcuate tubes, all of the aforesaid structurebeing a one piece iron casting, and each of said connectors being solidiron.

References Cited in the file of this patent UNITED STATES PATENTS663,658 Kellogg Dec. 11, 1900 970,483 Fiebeger Sept. 20, 1910 1,595,639Beard Aug. 10, 1926 1,641,999 Webster Sept. 13, 1927 1,733,158 KollaOct. 29, 1929 1,927,002 Olson Sept. 12, 1933 2,159,440 Livar May 23,1939 2,314,825 Herbster Mar. 23, 1943 2,336,609 Herbster Dec. 14, 1943FOREIGN PATENTS 20,762 Netherlands Nov. 15, 1929

